Commands:

cl_crosshairgap cl_crosshairgap [Gap] This console command will adjust the size of the gap in the middle of your crosshair. The smaller the value, the smaller the gap.
cl_crosshairsize cl_crosshairsize [Size] This command controls the length and size of the 4 lines that make up a standard crosshair. Using a low value will give your crosshair very slight lines, and using a large value makes your crosshair have very long lines.
cl_crosshairstyle cl_crosshairstyle [Style] This command sets the style of your crosshair such as its general shape and whether or not it opens up whenever your character moves around.
cl_crosshairthickness cl_crosshairthickness [Thickness] This console command customizes the thickness of your in game crosshair.
cl_crosshair_drawoutline cl_crosshair_drawoutline [0 / 1] This console command can be used to enable and disable the small black outline that is around your crosshair. This can enhance crosshair visibility for some players.
cl_crosshair_outlinethickness cl_crosshair_outlinethickness [Thickness] This useful console command adjusts how thick the outline of your crosshair is. It is an important command to adjust to ensure your aim is as good as it can be.
cl_crosshaircolor cl_crosshaircolor [Color] This console command sets the color that your crosshair shows up as. You can set a value between 0 and 4.
cl_crosshairalpha cl_crosshairalpha [Alpha Value] This command sets how transparent your crosshair is on your screen. The lower the value, the less visible your crosshair is.
cl_crosshaircolor_b cl_crosshaircolor_b [Blue Value] This console command allows you to set the color of your crosshair with detail, by adjusting its level of blue. The same command exists for red and green.
cl_crosshaircolor_g cl_crosshaircolor_g [Green Value] This console command allows you to set the color of your crosshair with detail, by adjusting its level of green. The same command exists for red and blue.
cl_crosshaircolor_r cl_crosshaircolor_r [Red Value] This console command allows you to set the color of your crosshair with detail, by adjusting its level of red. The same command exists for green and blue.
cl_crosshairgap_useweaponvalue cl_crosshairgap_useweaponvalue [0 / 1] When activated, this command will dynamically adjust the size of your crosshair depending on what weapon you have equipped at the time.
cl_crosshairdot cl_crosshairdot [0 / 1] This command adds a dot in the center of your crosshair. If you reduce cl_crosshairsize to 0, you can set it so you only have a dot.
cl_crosshair_dynamic_maxdist_splitratio cl_crosshair_dynamic_maxdist_splitratio [Ratio] This console command is what determines the ratio of the inner and outer lines when using the cl_crosshairstyle 2 command.
cl_crosshair_dynamic_splitalpha_innermod cl_crosshair_dynamic_splitalpha_innermod [Alpha Value] When using cl_crosshairstyle 2, this is the command that adjusts the transparency of the inner crosshair.
cl_crosshair_dynamic_splitalpha_outermod cl_crosshair_dynamic_splitalpha_outermod [Alpha Value] When using cl_crosshairstyle 2, this is the command that adjusts the transparency of the outer crosshair.
cl_crosshair_dynamic_splitdist cl_crosshair_dynamic_splitdist [Value] When using cl_crosshairstyle 2, this command sets how far apart the two crosshairs move apart when your character model moves.
cl_crosshairusealpha cl_crosshairusealpha [0 / 1] Adjusts the transparency of your crosshair.
crosshair crosshair [0 / 1] You can use this console command to toggle whether or not your crosshair is visible in game.
cl_fixedcrosshairgap cl_fixedcrosshairgap [Gap] This console command alters the gap inbetween the pips (the four lines that form a crosshair) when using the fixed crosshair.
cl_observercrosshair cl_observercrosshair [0 / 1] This is the console command that controls whether or not you have a crosshair when spectating/observing players.
light_crosshair light_crosshair This command prints the luxel value of your crosshair in the console.
cl_crosshair_sniper_show_normal_inaccuracy cl_crosshair_sniper_show_normal_inaccuracy [0 / 1] This command, if enabled (1), will make it so that standing inaccuracy will also affect the blur of a sniper's crosshair. By default, this is disabled (0).
cl_crosshair_sniper_width cl_crosshair_sniper_width [Pixels] This command sets the width, in pixels, of the width of the crosshair when scoped in with a sniper rifle.
cl_crosshair_t cl_crosshair_t [0 / 1] This command, if enabled (1), will make your crosshair a "T" style crosshair, in which the top line of the crosshair isn't drawn (so there are only 3 crosshair lines, not 4). Default is 0 (disabled / normal crosshair).